Trimming apparatus

1. A trimming apparatus for adjusting an electric property value of a trimming object circuit, the trimming apparatus comprising: a data input pad that is a single pad and that receives an input of serial data; a shift register that outputs parallel setting data by shifting the serial data received through the data input pad; a trimming data generating circuit that includes a plurality of trimming elements, each having a conductive part that is cuttable by a flow of an electric signal, a plurality of pull-up resistors respectively connected to high potential sides of the trimming elements, and a plurality of switches respectively connected to low potential sides of the trimming elements, the trimming data generating circuit being configured to generate trimming data for the trimming object circuit by switching the plurality of switches in accordance with a level of the setting data; and a cutting control circuit that controls application of the electric signal to the trimming data generating circuit.

2. The trimming apparatus according to claim 1 , wherein the trimming apparatus is configured to operate in one of three phases including: a trimming estimation phase in which the serial data received by the data input pad is serial data for estimation, the cutting control circuit stops applying the electric signal, the shift register shifts the received serial data for estimation to output the setting data, and the switches are turned on, when the setting data is at a first level, to output the trimming data at a low potential level, and are turned off, when the setting data is at a second level, to output the trimming data at a high potential level, to thereby preliminarily estimate a state of the trimming object circuit after trimming elements cutting; a trimming element cutting phase in which, for a prescribed one of the trimming elements, the cutting control circuit applies the electric signal, and the shift register outputs the setting data at the first level to one of the switches connected to the prescribed trimming element to turn on the one switch, so that the electric signal flows through the prescribed trimming element to cut the prescribed trimming element; and an actual operation phase in which, the cutting control circuit stops applying the electric signal, and the shift register outputs the setting data at the first level from all output terminals of the shift register to turn on all of the switches, so that the trimming data at the low potential level is output from an uncut one of the trimming elements, and the trimming data at the high potential level is output from an already-cut one of the trimming elements, to thereby perform an actual operation after the trimming element cutting phase.

3. The trimming apparatus according to claim 2 , wherein the serial data received by the data input pad in the trimming element cutting phase is obtained by inverting logic values of the setting data outputted from the shift register when a bit width to be set to the trimming object circuit is estimated in the trimming estimation phase.

4. The trimming apparatus according to claim 1 , wherein: the shift register outputs the parallel setting data by shifting the serial data by n bits, n being a positive integer; the shift register includes at least n serially connected flip-flops; in the trimming data generating circuit, the plurality of pull-up resistors include at least n pull-up resistors, the plurality of trimming elements include at least n trimming elements, and the plurality of switches include at least n NMOS (N-Channel Metal Oxide Semiconductor) transistors, the trimming data generating circuit further includes at least n buffers to buffer and output the trimming data; and the cutting control circuit includes at least n PMOS (P-Channel Metal Oxide Semiconductor) transistors.

5. The trimming apparatus according to claim 4 , wherein: gates of the n PMOS transistors are connected to a control signal input pad which receives an input of a control signal to control the application of the electric signal to the trimming data generating circuit; sources of the n PMOS transistors are connected to an electric signal input pad which receives an input of the electric signal; set terminals of the n flip-flops are connected to a set disable signal input pad which receives an input of a set disable signal; a data input terminal of one of the n flip-flops that is located at an initial stage is connected to the data input pad; and clock terminals of the n flip-flops are connected to a clock input pad.

6. The trimming apparatus according to claim 4 , wherein: the pull-up resistors each have a first end and a second end, the trimming elements each have a first end and a second end, the first ends of the pull-up resistors are connected to a high potential side of the trimming data generating circuit; the second ends of the pull-up resistors are connected to drains of the PMOS transistors, input terminals of the buffers, and the first ends of the trimming elements; output terminals of the buffers are connected to the trimming object circuit; the second ends of the trimming elements are connected to drains of the NMOS transistors; gates of the NMOS transistors are connected to output terminals of the shift register; and sources of the NMOS transistors are connected to a low potential side of the trimming data generating circuit.